XCMG XE15 Mini Excavator Fault Code 155: Meaning, Symptoms & Fix

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What is XCMG XE15 Fault Code 155?

XCMG XE15 Fault Code 155 indicates a fault in the engine speed sensor signal circuit — specifically, an abnormal or out-of-range signal detected by the Engine Control Module (ECM) from the crankshaft position sensor (CKP) or camshaft speed sensor.

On the XCMG XE15 mini excavator, the ECM continuously monitors engine RPM data to manage fuel injection timing, hydraulic pump control, and idle stability. When this signal is lost, erratic, or falls outside the acceptable voltage threshold, the system logs Code 155 and may trigger a protective response to prevent engine damage.

This fault is considered critical because accurate speed signal data is fundamental to every aspect of engine management. Ignoring it can lead to progressive fuel system damage or complete engine shutdown in the field.

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Common Symptoms

When Fault Code 155 is active on the XCMG XE15, operators typically experience:

• Warning light illuminated on the instrument cluster (engine or fault indicator)
• Unstable idle or sudden RPM fluctuations under load
• Hard starting or no-start condition — the ECM cannot confirm engine position for injection timing
• Reduced hydraulic response due to the ECM entering a protective derate mode
• Engine stalling unexpectedly, particularly at low idle or during transitions between work modes

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Potential Causes

The following are the most common technical causes behind Fault Code 155 on this machine:

• Failed or worn crankshaft/camshaft position sensor — common on higher-hour used units
• Damaged or chafed sensor wiring harness — particularly near the engine block where harnesses contact hot or vibrating surfaces
• Corroded or loose connector pins at the sensor plug or ECM harness connector
• Incorrect air gap between the reluctor ring and the speed sensor tip (typically should be 0.5–1.5mm)
• Damaged tone ring (reluctor wheel) — cracked or missing teeth cause signal dropout
• ECM internal fault — less common but possible on machines with prior electrical damage or improper repairs

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How to Troubleshoot and Fix Fault Code 155

Step 1 — Retrieve and Document the Code Connect XCMG-compatible diagnostic software (such as the XCMG Diagnostic Tool or a compatible J1939 reader) to the OBD port. Record all active and stored fault codes. Note whether Code 155 is intermittent or permanent, as this guides the diagnosis.

Step 2 — Inspect the Harness and Connectors On used excavators, harness wear is the most frequent root cause. Physically trace the speed sensor wiring from the sensor to the ECM. Look for:

• Rub marks or abrasion against the engine block or brackets
• Melted insulation near exhaust components
• Green corrosion or bent pins inside the connector

Clean connectors with electrical contact cleaner and apply dielectric grease before reconnecting.

Step 3 — Test the Sensor Using a digital multimeter, measure the sensor's resistance across its terminals. Most inductive-type speed sensors on this platform read between 800–1,200 ohms. A reading outside this range indicates a failed sensor requiring replacement.

Step 4 — Check the Air Gap Using a feeler gauge, verify the gap between the sensor tip and reluctor ring. Adjust if necessary according to the XCMG XE15 service specification.

Step 5 — Inspect the Tone Ring Visually inspect the reluctor wheel for cracked, chipped, or missing teeth. A damaged tone ring requires crankshaft or flywheel housing disassembly for proper repair.

Step 6 — Clear and Retest After repairs, clear the fault code using diagnostic software and run the engine through full operating RPM range. Confirm the code does not return.

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Disclaimer: This guide is intended for informational purposes and general diagnostic reference. Always consult the official XCMG XE15 service manual and follow proper safety procedures before performing electrical or mechanical repairs. For complex ECM faults or internal engine issues, consult a certified heavy equipment technician or authorized XCMG service center.